1. Field of the Invention
The present invention relates to an on-vehicle information processing unit that meets the requirement of high-speed processing such as map drawing.
2. Description of Related Art
FIG. 16 is a block diagram showing a hierarchical configuration of a conventional navigation system. In FIG. 16, the reference numeral 101 designates navigation hardware including a DVD-ROM drive, a display monitor, a GPS receiver, a vehicle speed pulse counter, a gyroscope and the like. The reference numeral 102 designates a navigation OS (operating system) including basic functions such as memory management of programs, process management and thread management in conjunction with a function of controlling navigation hardware 101. The reference numeral 103 designates a graphic-chip-only device driver for directly controlling a graphic chip of the navigation hardware 101; 104 designates a navigation application; and 105 designates an Internet browser for carrying out program communications with the navigation application 104 via an external interface (I/F) 104a. 
Next, the operation of the conventional navigation system will be described.
Starting its operation, the navigation application 104 commands the graphic chip 101a to execute a display operation through the graphic-chip-only device driver 103, thereby carrying out high-speed drawing. In the display state, the navigation application 104 starts the Internet browser 105 through the external I/F 104a to display an Internet browser screen on the graphic chip 101a. 
With the foregoing configuration, the conventional on-vehicle information processing unit executes a program using the dedicated driver (graphic-chip-only device driver 103) to achieve the best performance of the device (graphic chip 101a) without using drivers installed in the operating system (OS). Accordingly, a general-purpose application, which is designed to operate using the drivers prepared in the OS, cannot work without change. To enable its operation, it is necessary for the general-purpose application like an Internet browser to use a device driver specifically designed for the application in accordance with the rule proper to the device driver. Thus, the dedicated device driver suitable for the general-purpose application must be developed. This presents a problem of requiring a large number of man-hours to develop it, making it difficult to utilize the available resources of the general-purpose application.
For example, when a system is configured such that it operates the navigation application (device-dependent application) on the Windows CE by using a dedicated device driver, a problem arises that the system cannot make use of general-purpose applications like an Internet browser, so-called Windows applications, which utilize GDI (graphics device interface) compatible device drivers that employ a common interface, and hence adapt to different drawing devices.
The present invention is implemented to solve the foregoing problem. It is therefore an object of the present invention to provide an on-vehicle information processing unit extending its applications and implementing high-speed processing at the same time.
According to one aspect of the present invention, there is provided an on-vehicle information processing unit comprising: a central processing unit; a device connected to the central processing unit; a device-dependent driver for driving only the device; an operating-system-standard (OS-standard) driver enabling an application to drive different devices; a device-dependent application for using the device through the device-dependent driver; and an operating-system-dependent (OS-dependent) application for using the device through the OS-standard driver.
Here, the central processing unit may comprise switching means for enabling the OS-dependent application only when using an Internet function, and for operating the device-dependent application in a normal mode.
The device-dependent driver may further comprise driver switching means for switching between the device-dependent driver and the OS-standard driver.
The device-dependent application may control the driver switching means by carrying out inter-program communication with the OS-dependent application.
The on-vehicle information processing unit may further comprise a device driver switching module for enabling the device-dependent driver in response to a request of the device-dependent application, and for enabling the OS-dependent driver in response to a request of the OS-dependent application.
The device driver switching module may enable one of the device-dependent driver and OS-dependent driver in response to an operation of a manual switch.
The central processing unit may further comprise a program managing module for controlling execution of the device-dependent application and the OS-dependent application, and the device driver switching module switches the device drivers in response to a request of the program managing module.
The device may be a display device having multi-display layers, and display an image associated with the device-dependent application on an upper layer, and an image associated with the OS-dependent application on a lower layer.
The device may simultaneously display images associated with both the device-dependent application and the OS-dependent application by limiting at least one of display areas of the upper display layer and the lower display layer.
The OS-dependent application may operate on a virtual machine.